Apparatus for pickling plates



Sept. 11, 1951 c. G. WATSON I 2,567,415

APPARATUS FOR PICKLING PLATES Filed Spt. 25, 1947 4 Sheets-Sheet 1 A N NI III INVENTOR.

A T TOR/YE Y5 4 Sheets-Sheet 2 0 W W W 2 I mMm/ s M w W a z n M v l c.G. WATSON APPARATUS FOR PICKLING PLATES Sept. 11, 1951 Filed Sept. 25,1947 ATTORNEYS Sept. 11, 1951 c. e. WATSON APPARATUS FOR PICKLING PLATES4 Sheets-Sheet 5 Filed Sept. 25, 1947 BY M 13 ATTOR/VEXS m T N m w 3E mN W J 6 HM & & WW x WM Q a 1H m U 9 o u 0 D U D L R H m .3 H .8 m C w w1 1w ulfliiffi-nili|uuvu%ki m n" M m" NW mm m .an v Jcu fq 1 m a xPatented Sept. 11, 1951 APPARATUS FOR PICKLING PLATES Charles G. Watson,Youngstown, Ohio, assignor to The Youngstown Welding. & EngineeringCompany, Youngstown, Ohio, a corporation of Ohio Application September25, 1947, Serial No. 776,078

13 Claims.

tus-for simultaneously pickling a plurality of sheets or plates, whichapparatus assures contact of the entire surfaces of the sheets or-plateswith .the pickling solution and can be assembled from readily available,inexpensive equipment.

Another object of the invention is the provision of a novel and improvedapparatus of the character referred to wherein a plurality of sheets orplates are supported on edge by a fiat or straight surface and caused totilt through a limited movement relative to said surface whereby thead-. joining sides of adjacent sheets or plates are moved'slightlyrelative to eachother, thus facilitating the penetration of the picklingliquid between the sheets or plates and the removal of scale therefrom.

Another object of the invention is the provision of a novel and improvedapparatus for pickling plates or the like, which apparatus comprises asubstantially straight surface upon which a plurality of plates areadapted to be supported on edge for limited tilting movement,in'combination with means for causing the plates to tilt on saidsupporting surface and the adjoining sides of adjacent plates to moverelative to each other.

Further objects and advantages of the invention will be apparent tothose skilled in the art to which it relates from the followingdescription of the preferred apparatus described with reference to theaccompanying drawings forming a part of this specification in whichsimilar reference characters designate corresponding parts, and in whichFig. 1 is a plan view of the present preferred form of a picklingapparatus embodying the present invention;

Fig. 2 is a sectional view, approximately on the line 2-2 of Fig. 1 andshowing plates to be pickled in place in the apparatus;

Fig. 3 is a sectional view, approximately on the line 3--3 of Fig. 1.;

Fig. 4 is a plan View of a modified form of a pickling apparatusembodying the present invention with the crate or framework forsupporting the plates to be pickled removed;

Fig. 5 is a sectional View, approximately on Fig. 7 is a fragmentary endelevational view of one of the crates of the apparatus in one of itstilted positions and illustrating the resulting positions of the platestherein; and

Fig. 8 is a view similar to Fig. 7 but with the crates of the apparatusin another of its tilted positions and illustrating the resultingpositions of the plates therein.

Referring first to Figs. 1 to 3 of the drawings, which illustrate thepresent preferred form of the apparatus, the reference character Adesignates a, tank which may be of any conventional construction andmade of any suitable material resistant to the pickling solution withwhich it is filled substantially to the top. The tank shown is ofelongated, rectangular shape in plan view, as is the usual practice. Thetank per se forms no part of the present invention and is not hereindescribed in detail. The tank A is provided with a cradle B made ofMonel metal or some other suitable material resistant or inert to thepickling solutionand adapted to carry two crates C hereinafterdescribed. The cradle comprises a plurality of transversely extendingmembers I0 suspended by vertically extending members I I, 62 at oppositesides of the tank. Four transversely extending members In are shown butit is to be understood that a greater number may be used depending upon.the length of the tank and the construction of the crates or frameworkshereinafter referred to, which support the plates to be pickled and are,in turn, supported by the cradles. Opposite ends of the members I0 arepivotally connected to the members or rods II, I2 as by pins I3. Theupper ends of the members or rods I I, I2 are pivotally connected bypins I4 to arms I5, It, respectively, which are in turn fixed-to,ilongitudinally extendin shafts I'I, I8. These arms extend inwardlytoward the longitudinal centerline of the tank so that the members orrods I I, I2 are substantially vertical when the members III arehorizontal. The longitudinally extending shafts are rotatably supportedin suitable bearing brackets 20 bolted or otherwise secured to supportsor pillars 2I at oppositesides of the tank. In the present instance thesupports Zl are shown as concrete piers; however, other constructionsmay be employed or the shafts may be supported on the tank proper. Withthe preferred arrangement, the tank A can be replaced without disturbingother parts of the equipment.

The plates or sheets P to be pickled are sup ported in upstandingrelationship by crates or frameworks C which are adapted to be readilyimmersed in the pickling solution in the tank and to be removedtherefrom. As shown, there are two crates or frameworks C but a singlecrate or framework may be employed if the plates P are of great length.When a crate or framework is in the tank it rests upon one or more ofthe members I of the cradle B and is rocked and lifted thereby ashereinafter described. Each crate or framework C is illustrated ascomprising a bottom portion to which are attached longitudinally andupwardly extending spaced portions forming a plurality of compartmentsfor the plates P. As shown, the bottom portion of the crate or frameworkis formed by pairs of spaced transversely extending bars 22 to whichvertically extending portions or walls 23 are attached. The walls 23 arepreferably formed of plates provided with suitable openings to permitthe free flow of the pickling solution therethrough and the ends of thecrate or framework are open. Alternatively, the vertical plates or walls23 may be replaced by vertically extending bars or by a combination ofvertically and longi tudinally extending bars if desired. Also, thebottom portion of the crate or framework may be formed by a plate orplates with or without openings if desired. The crates or frameworks Care preferably constructed of Monel metal or other suitable materialwhich is resistant or inert to the pickling solution.

In the illustrated form of the crates or frameworks, six verticallyextending members have been shown providing two side walls or membersand four partition walls or members, thus forming five compartments foreach framework. Obviously, a greater or lesser numer of such wallmembers may be employed and in certain instances no partition walls arenecessary. Also, the spacing between the vertical members or walls 23may be varied and it isnot necessary that all of the compartments havethe same width. The width of the compartments is dependent upon the sizeof the plates to be treated, the number placed in each compartment andthe amount of tilting or rocking which it is desired to impart to theplates. The width of the compartments-is preferably less than the widthof the plates P to be supported therein so that even if only a fewplates are placed in a compartment they will be supported with theirplanes extending generally vertically. As shown in Fig. '2, the plates Pare placed in the crate or framework in a manner such that they stand onedge and so that there is room for the plates to tilt about their loweredges or corners relative to the framework when the latter is rocked sothat adjoining sides of adjacent plates strike and rub together and theouter plates in each compartment strike or rub against the members orwalls 23 of the framework.

Preferably, the plates P are loaded into the crates or frameworks beforethe latter are placed in the tank A and the frameworks are their loweredinto the tank so as to rest upon the transverse members I I] of thecradles B. This may be effected by providing a plurality of chains orother flexible supporting means 24 for each framework, the lower ends ofthe chains being attached to the crates or frameworks adjacent thecorners thereof. The upper ends of the chains are free and are adaptedto be engaged by hooks 25 supported upon transverse beams or members 26which form a part of, or are attached to, a crane or the like, notshown. After a crate or framework has been positioned within the tank A,and rests upon the cradle as shown in Fig. 2,

the upper ends of its chains 24 are disconnected from the hooks 25 andthe said upper ends of the chains may then be supported upon fixed hooks21 fastened to the tank A adjacent the top thereof. The chains or cables24 should have sufficient slack, when supported as shown in Fig. 2, soas not to interfere with the rocking and lifting movements of the crateor framework.

In order to effect movement of the cradles B and of the crates orframeworks C to produce tilting of the plates P, the shafts I1 and I8are provided with a mechanism for efiecting rocking thereof. As shown inFigs. 1 and 3 this rocking mechanism comprises arms 28 and 29 which areattached to the shafts I1 and I3, respectively, the outer ends of thesearms being pivoted to the upper ends of links 30--and 3I. The lower endsof the links 30 and 3| are pivoted to a crankpin in the form of a shortshaft 32 which is non-rotatably mounted in the outer ends of crankarms33 and 34. The crank arm 33 has its inner end connected with a shaft 35which is the output shaft of a speed reduction unit 36 driven by a motor31. The inner end of the crank arm 34 is provided with a stub shaft 38journaled in a bearing bracket 39 which, together with the motor and thespeed reduction unit, are supported upon a suitable pier or pillar 48adjacent one end of the tank A.

Referring to Fig. 3, it will be observed that when the shaft 35 isrotated, the crank arms 33 and 34 will cause the center of the commonpivot for the links 30 and 3I, that is, the crank pin or shaft 32, todescribe a closed path which in this instance is a circle, indicated bybroken lines and designated D. This will cause the, links 30 and 3| torock the arms 28 and 29 and hence the shafts I! and I8, thereby rockingthe cradle B and the framework or frameworks C. For the purpose ofillustrating the motion imparted to the arms 28 and 29, and hence toeach cradle and framework, four positions of the center of the commonpivot 32, spaced apart in its path, have been designated I, 2, 3 and 4and the corresponding positions of the arms 28 and 23 for each of thesepositions of the pivot 32 are indicated by broken center lines bearingcorresponding numerals. It will be observed, therefore, that with theparts as shown in Fig. 3 the center of the common pivot of the links isat position I in its circular path D and the arms 28 and 29correspondingly occupy positions I. At this time the shafts I1 and I8and the arms I5 and I6 attached thereto occupy the positions as shown inFig. 2 so that the cradle B and the crates or frameworks C aresubstantially horizontal and disposed at their lowermost positions. Whenthe center of the common pivot 32 of the links 3|], 3| has moved to theposition designated 2, the link 3| will have elevated the arm 29slightly to its position designated 2 in Fig. 3, while the link 30 willhave elevated the arm 28 a greater extent to its position 2.Consequently, the shafts I1 and I8 will be rocked different amounts sothat the arms I5 and I8 are raised to different elevations correspondingto those of the arms 28 and 29, respectively. This results in the cradleB and the frameworks C being rocked or tilted within the tank and hencethe plates P will tilt about their lower edges relative to theirframework or crate C. The positions assumed by the crates or frameworksC and the positions of the plates P therein will, therefore, besubstantially as illustrated in Fig. 7. Since measure 5 the. plates Pwhich are to. 'bepickled generally are or appreciable thickness, theywill be rocked or tilted about their corresponding longitudinallyextending lower edges or corners P :Hencaadjacentsides or 'faces ofthezplates come into engagement and slide "relative tov each as thecrates'or frameworks move from the position illustrated Eig. 2 to thatillustrated inFig. '7. liaise, the 'outer plate at the right-hand "side0f leach compartment-"will strike and/or rub against the adjacentpartition wall -23. This relative sliding rand-hr striking ofthesplates. together and with the .partition walls. loosens. and/orremoves scale or oxides. thereon and ensures a thorough wetting andtreatment of the plates by the pickfiling solution. As mentioned before,the amount 'of' the tilting of the plates. is dependent upon the widthof the compartments in the cradles "orlframeworks =0; and upon the sizeand number "of plates supported in each compartment.

When the center .of the common, pivot 32 of linksv 31 9., 3 has reached"the position 3 in its circular path both the arms 28 and 729 willoccupy their uppermost positions, designated 3 in Fig. 3; and'atPthistime the cradle B and irameworks or cratesC: will besubstantially horizontal and in their uppermost position within the tankAs the cranks 3.3 and 34 continue to rotate, the. center of thecommonpivot 32 of the 13a, 13! moves to position ll, thus moving thelinks 30, 3| and rocking the arms 28, 2.9 to their positions designated4. Hence, the cradle B and crates 'C' are now rocked or tilted in areverse direction to that in which they were tilted when the center ofthe common pivot. 32 was. atv position :2 so. that the plates P' havenow been rockedor tilted relative to their framework or crate in theopposite. tii'rection to. thatr-in which they were previously rocked ortilted. The plates P now assume a position somewhat similar to thatillustrated in Fig. 8, from which it will be seen that the plates P havenow rocked or tilted about their other lower longitudinally extendingedges or corners: P so. that adjacent f'ace's or sides of the plateshave again moved or slid relative to. each other and the outer plates atthe left-hand side of each compartment has struck or rubbed against theadjacent wall :23. This rocking and lifting motion is continuouslyrepeated so. long" as the. motor 31 is in opera?- tion and consequentlythe plates P rock. or tilt relative to. their framework or crates C.- sothat the said plates strike and rub against each other and the adjacent.side; walls or partition walls of the framework- Asmentioned'before,this f'acilitates the loosening of the scale upon the plates P and theentrance of the picklingfluid-therebetween so that the plates may becompletely treated in: much shorter time than has heretoforebeerrpossible.

In Figs. 4 and 5.:of the drawings is illustrated a modified form ofapparatus embodying this invention. As inthe preferred form, of theapparatus, a. pickling: tank is; proyided and adjacent thelengitudinalsides of the tank, at spaced points therealong, are located pillars orpiers; 2 l, the-upper ends of which; support bearing brackets at. Thesebearing brackets are substantially the same as thev bearing brackets 20of the preferred form except that they do not over-- hang. a. portion ofthe tank. The bearing brackets. 20" support. the. longitudinallyextending shafts H. and I13 which are provided with arms I35, Hi, 28 andill-as in the form of the apparatus illustrated in the Figs. I to 3.Also, asv in the do "not rest upon a submerged cradle.

"6 previously described form of apparatus-"the shafts I1 and 18 0f thepresent formare actuated in the sam'o mannerby employing links 39, 31which are pivoted together and driven by the motor '31 through the gearreduction unit dB-as was previ ously described;

The crates or frameworks. C employed "in this form of the apparatus areconstructed in the same manner as thecrates-emplo'yed in the previously-described embodiment. In the present embodiment, however, thecrates or frameworks "C Instead the bars '22 of the bottom portion ofeach framework or crate are provided with longitudinally extendingrpivot-ipins 4'! each of which is adapted to be received between a pairof spaced upwardly extending ears 42 mounted in the bottom of the tank Awhen the crate or framework C is placed therein. In addition, the chains2d, which are attached to the bars 22, now have their upper endsreceived upon hooks 43 which are connected with a transversely extendingmember '44, there being at least two such transversely extending membersfor each crate'or framework and preferably spaced adjacent the ends ofthe latter. The transversely extending members or bars 134 are eachprovided with a loop 45 adapted to be engaged by a crane or otherlifting means for i-ais ing and lowering the crate or framework Crelative -to the tank A.

When each crate or framework C is positioned within the tank A as shownin Fig. 5', the pivot pins '4'! are received between the ears 42as-p'reviously mentioned and -inaddition, the lower surface of the barsor members 44 rest upon the upper surface of longitudinally extendingbars at. and 41 The transverse members or bars 44 are guided into properposition relative to the bars 45 and 4.1, when being placed thereon, bydownwardly extending angular members 48 and 49 attached to the lowersurface of the bars M and cooperating with the bars '46 and 4'! tocenter the crate or framework 0 so that the; pivot pins M are properlydisposed Within the ears '42. The bars 45 and l-2' extend longitudinallyadjacent to, but spaced from the upper surface 'of the tank A, and arepivotally connected, as by means of short. links 59 and El, to the arms15 and I6 carried. by the shafts I! and I 8.

the construction just. described, energi'zation of theumotor 31 causesthe shafts; I1 and, I8, and hence the. arms {-5 and 16, to be rocked inthe manner described with respect. to the preferred embodiment. Hence,the longitudinally extending members orbars A5 and 41 are elevated andlowered varying amounts thereby causing rocking and lifting motion ofthe crates or frameworks C and. the plates P supported there-in, thismotion being, transmitted from-the members 46 and 41. to the crates orframeworks by the transversely extending members M and thechains 24Therefom, each crate. or framework Q is. rocked about a longitudinalaxis corparatus the operation, briefly summarized, comprises supportingthe plates P in upstanding relationship upon a surface with the platesimmersed in a pickling solution and then rocking the supporting surfaceso as to cause the plates to tilt relative thereto about their lowercorners or edges as axes and to strike and rub against each other. Thisrepeated striking and rubbing as the plates tilt or rock facilitates theremoval of scale thereon and the penetration of the pickling solutiontherebetween.

The operation as briefly summarized above may be advantageously effectedby placing a plurality of plates P in upstanding relationship in one ormore crates or frameworks, such as those disclosed in the drawings andas described above, which are so constructed that the plates may tiltabout their lower edges P and P but cannot fall upon their sides. Thewidth of the compartments in each crate or framework will, of course,depend upon the size and number of plates to be supported therein andthe amount of tilting to be imparted to the plates. The plates should beloosely disposed in the said crate or framework to permit the desiredamount of tilted action. With the plates so positioned, each crate orframework is then lowered into the pickling solution within the tank Auntil it is supported as shown in either Fig. 2 or Fig. 5 depending uponthe form of apparatus employed. The motor 31 is then started, thuscausing rocking, lifting and lowering of each crate or framework byvirtue of the movement of the cradle B, or of the longitudinal members46, 41, as the result of the operation of the links 30, 3|, shafts l1,l8 and the arms connected therewith. After the rocking, raising andlowering of the frameworks and plates has continued for a sufficientperiod of time the motor 31 is stopped and the crates or frameworks areremoved from the tank A by means of a crane or the like.

At various points in the specification and in the claims the articlestreated in the pickling solution are referred to as plates. This term isused, and intended to be interpreted, in its generic sense as comprisingany metallic member whose thickness is less than its width and isinclusive of sheets and other similar commercially known shapes.

. While a preferred embodiment of the apparatus and one modificationhave been disclosed in considerable detail it will be readily understoodthat numerous variations may be made in the construction and arrangementof parts by one skilled in the art without departing from the basicconcept underlying the invention. Therefore, it is to be understood thatthe invention is not considered as limited to the exact details ofconstruction herein illustrated and described but only as required bythe spirit and scope of the appended claims.

Having thus described my invention, I claim:

1. An apparatus for pickling metal plates comprising an elongated tankadapted to contain a pickling solution, a framework for supporting theplates to be pickled in upstanding relationship, the said frameworkincluding a bottom portion and a plurality of upwardly extendingportions attached to said bottom portion in parallel spacedrelationship, cradle means movably supported in said tank and havingmembers thereof removably supporting said framework in said tank so thatthe plates supported by the framework are immersed in the picklingsolution, and means for rocking said cradle means to thereby rock theIll said framework transversely of said tank, thus causing the plates totilt relative to said framework so that adjoining sides of adjacentplate are moved relative to each other.

2. A pickling apparatus of the type defined in claim 1 and in which themeans for rocking said cradle means includes a pair of links, meansoperatively connecting the corresponding end of each link totransversely spaced points onsaid cradle means, means pivoting the otherends of said links together, and means for moving the common pivot ofsaid links in a closed path.

3. An apparatus for pickling metal plates comprising an elongated tankadapted to contain a pickling solution, a framework for supporting thelates to be pickled, the said framework including a transverselyextending bottom portion and a plurality of upwardly extending portionsattached to said bottom portion in parallel spaced relationship toprovide a plurality of longitudinally extending spaces in which theplates to be pickled are placed, the spacing between adjacent ones ofthe vertically extending portions being less than the width of a plateplaced therein so that the plates are supported with their planesextending substantially vertically, means for removably supporting saidframework in said tank so that the plates supported by the framework areimmersed in the pickling solution, and means for repeatedly rocking saidlast-mentioned means to thereby rock said framework transversely of saidtank, thus causing the plates to repeatedly tilt relative to saidframework so that adjoining sides of adjacent plates are moved relativeto each other.

4. A pickling apparatus of the type defined in claim 3 and furthercomprising means on the bottom portion of said framework cooperatingwith means on the bottom of the tank, when the framework is positionedin the latter, to provide a longitudinally extending pivotal axis forsaid framework.

5. An apparatus for pickling metal plates com- .prising an elongatedtank adapted to contain a pickling solution, a framework for supportingthe plates to be pickled in upstanding relationship within the picklingsolution in said tank, the said framework including a transverselyextending bottom portion and a plurality of upwardly extending portionsattached to said bottom portion in parallel spaced relationship toprovide a plurality of longitudinally extending spaces adapted toreceive plates to be pickled, the spacing between adjacent ones of thevertically extending portions being less than the width of a plateplaced therein so that the plates are supported with their planesextending substantially vertically, means on said bottom portioncooperating with means on the bottom of the tank when the framework ispositioned therein to provide a longitudinally extending pivotal axisfor said framework, and means for rocking said framework about itspivotal axis thus causing the plates to tilt relative to said frameworkso that adjoining sides of adjacent plates are moved relative to eachother.

6. A pickling apparatus of the type defined in claim 5 and in which themeans for rocking said framework includes a pair of spacedlongitudinally extending shafts, transversely extending arms attached tosaid shafts and operatively connected with the said framework, a pair oflinks, one end of one link being pivotally connected with a transverselyextending arm attached to one of said shafts and the corresponding endof the other link being pivotally connected to a transversely extendingarm attached to the other of said shafts, the other ends of said linksbeing pivoted together, and means for moving the common pivot of saidlinks in a closed path.

'7. An apparatus for pickling metal plates comprising an elongated tankadapted to contain a pickling solution, a framework for supporting theplates to be pickled in upstanding relationship, the said frameworkincluding a transversely extending bottom portion and a plurality oflongitudinally and upwardly extending portions attached to said bottomportion in parallel spaced relationship, means for removably supportingsaid framework in said tank so that the plates supported by theframework are immersed in the pickling solution, pairs of aligned spacedupstanding ears in said tank, longitudinally extending pivot pinsattached to the bottom portion of said framework and adapted to bereceived between said spaced ears when the framework is positioned insaid tank to thereby provide a longitudinally extending pivotal axis forsaid framework, and means for rocking said framework supporting means tothereby rock said framework about its pivotal axis thus causing theplates to tilt relative to said frame work so that adjoining faces ofadjacent plates are moved relative to each other.

'8. An apparatus for pickling metal plates comprising an elongated tankadapted to contain a pickling solution, a framework for supporting theplates to be pickled including a transversely extending bottom portionand a plurality of upstanding and longitudinally extending portionsattached to said bottom portion and adapted to support plates to bepickled in upstanding relationship, means for removably supporting saidframework in said tank including a pair of spaced longitudinallyextending members disposed adjacent the top of said tank, a plurality oftransversely extending members adapted to rest upon said longitudinallyextending members, means connecting said transversely extending memberswith the bottom portion of said framework, and means for raising andlowering said longitudinally extending members in a manner such that thesaid framework is rocked transversely of the said tank thus causing theplates to tilt relative to said framework so that adjoining sides ofadjacent plates are moved relative to each other.

9. A pickling apparatus of the type defined in claim 8 and furthercomprising means on the bottom portion of said framework cooperatingwith means on the bottom of the tank, when the framework is positionedtherein, to provide a longitudinally extending pivotal axis for saidframework.

10. An apparatus for pickling metal plates comprising an elongated tankadapted to contain the pickling solution, a framework for supporting theplates to be pickled in upstanding relationship, the said frameworkincluding a transversely extending bottom portion and spaced upwardlyand longitudinally extending portions attached to said bottom portion, acradle for removably supporting said framework in said tank so that theplates supported by the framework are immersed in the pickling solution,and means for supporting and rocking said cradle to thereby rock saidframework transversely of said tank thus causing the plates to tiltrelative to said framework so that adjoining sides of adjacent platesare moved relative to each other.

11. A pickling apparatus of the type defined in claim 10 and in whichthe means for rocking said cradle includes a pair of links, meansoperatively connecting the corresponding ends of each link to oppositesides ofsaid cradle respectively,

means pivoting the other ends of said links together, and means formoving the common pivot of said links in a closed path.

12. An apparatus for pickling metal plates comprising an elongated tankadapted to contain a pickling solution, a framework for supporting theplates to be pickled in upstanding relationship, the said frameworkincluding a transversely extending bottom portion and spaced upwardlyand longitudinally extending portions attached to said bottom portion, aplurality of members ex tending transversely of said tank in spacedrelationship to the sides and bottom of the latter and adapted to havethe framework supported thereon, pairs of vertically extending memberspivotally connected adjacent their lower ends to said transverselyextending members adjacent the ends of the latter, and means for raisingand lowering said vertically extending members in a manner such thatsaid transversely extending members and said framework are rockedtransversely of said tank thereby causing the plates to tilt relative tosaid framework so that adjoining sides of adjacent plates are movedrelative to each other.

13. A pickling apparatus of the type defined in claim 12 and in whichthe means for raising and lowering said vertically extending membersincludes a pair of spaced longitudinally extending shafts, transverselyextending arms attached to said shafts and pivotally connected with thesaid vertically extending members, a pair of links, one end of one linkbeing pivotally connected with a transversely extending arm attached toone of said shafts and the corresponding end of the other link beingpivotally connected to a transversely extending arm attached to theother of said shafts, the other ends of said links being pivotedtogether, and means for moving the common pivot of said links in aclosed path.

CHARLES G. WATSON.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 48,918 Ells July 25, 18651,393,633 Moltrop Oct. 11, 1921 1 1,491,602 Fuller Apr. 22, 19241,859,085 Haller May 17, 1932

